UNLV Geoscientist Steve Rowland is studying reptile-like tracks recently discovered on a boulder along the Bright Angel Trail in the Grand Canyon after a cliff collapsed. The tracks leave a perplexing trail of footprints left behind by a creature around 310 million years ago. Rowland and other scientists are trying to discover the secrets embedded in the boulder's 28 indentations, which may be among the earliest reptile tracks on Earth.